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(Nomodel') E c FITCH WATCH CASE. No. 289,340. Patented Nov. 27, 1883.

.Wflraaas'ea: Inuanisar:

UNITED STATES PATENT OFFICE.

EZRA C. FITCH, OF NEW YORK, N. Y., ASSIGNOR TO ROBBINS & APPLETON, OF SAME PLACE.

WATCH-GAS E.

SPECIFICATION forming part of Letters Patent No. 289,340, dated November 2'7, 1883. Application filed February 15. 1883. (No model.)

.10 all whom, it may concern: gold, and they are so disposed as to produce Be it known that I, EZRA O. FITCH, of New the greatest benefits. The outer layer, being York, in the county of New York and State of of a high grade, admits of a fine finish, and is New York, have invented certain Improveleast liable to become tarnished or oxidized by 5 ments in YVatchCases, of which the following handling or exposure. The inner layer of the is a specification. lower grade adds to the strength and stiffness This invention consists in making a watch of the case, and while it is susceptible to a case of two layers of gold, one of which forms high polish it is more liable to become tarthe outer and the other the inner surface of nished; but by my arrangement it is in such IO the case. Thetwo layers are of different qualia position as not to be exposed to the same extiesof gold, the outer layer being of a higher tent as the higher grade. If the high-grade quality than the inner, so that the external gold wears away, the case will still show a surface of the case is richer in appearance and gold surface at the points of wear. The two material than the internal surface. The two qualities of the metals have substantially the I 5 qualities are so proportioned that when melted same coefficient of contraction and expansion and mixed the mixture will be a standard and the same electrical potential, thereby quality of gold. For example, in a case comavoiding any mechanical or galvanic actionif posed of an outer layer of eighteen carat and exposed to variations of temperature oragalan inner layer of twelve carat gold, the two vanic excitant. This is not true of a case com- 2o qualities should be so proportioned as to melt posed of two different metalsas gold and a to a given standard, say, of fourteen carats. baser metaland is one of the objections to The two layers of gold are joined together in the use of such metal. the plate by rolling, and'formed into watch- I claim cases by dies or by any other suitable means. 1. A compound plate for watch-cases, con- 2 5 The accompanying drawing, forming a part sisting of two plates, one of gold of low standof this specification, represents a sectional ard, the other of gold of higher standard,rolled view of a watch-case back constructed in actogether, the relative thickness of the two cordance ,with my invention, the unshaded plates being so adjusted with relation to their portion a representing the inner layer and the relative fineness that the compound plate shall 30 shaded portion Z) the outer layer. It will be equal gold of a predetermined standard.

observed that a case thus constructed is, as a 2. A watch-case consisting of two plates,one whole, of a given standard of gold, and can be for the inner side of lower standard, the other guaranteed as such, and at the same time prefor the outside of higher standard, rolled tosents an external surface of greater value and gether and formed into the desired shape, the 3 5 richness than said standard. relative thickness of the two plates being so Filled cases have heretofore been made in adjusted with relation to their relative finethree layers-viz., an outer and an inner layer ness that the compound plate shall equal gold of gold and an interposed layer of base metal, of a predetermined standard. but the gold of both layers has been invaria- In testimony whereof I have signed my name 8 4o bly of the same quality, so far as I am aware. to this specification in the presence of two sub- My improved case is composed entirely of the scribing witnesses. two layers of gold differently alloyed, the outer layer being of a higher standard than the inner, as above described. By this construction lVitnesses: 5 I am enabled to make a watch-case having all A. M. CORUNNELIN,

the advantages of the different qualities of the 1?. IV. CARTER.

EZRA C. FITCH. 

